The present invention relates to a valve spring assembly.
Known valve spring assemblies include a valve spring plate which can be mounted to a valve stem and which supports a valve spring. The valve spring plate is retained on the valve stem by means of locking means, such as clamping cones or retaining rings, etc. Such valve spring assemblies, valve spring plates and installation methods are used in the manufacture of drives, machines or vehicles.
German patent 44 21 408 shows a valve spring assembly with a hollow valve spring plate and a valve spring that engages a rim region of the valve spring plate, which can be attached to the stem of a valve of an internal combustion engine. In order to secure the valve spring plate to the valve stem, the valve spring assembly is provided with a locking element that is formed by clamping cone halves. Retaining projections or brackets are provided on the valve spring plate to secure the locking element in an inner region of the valve spring plate against loss.
Accordingly, an object of this invention is to provide a valve spring assembly which can be easily installed.
These and other objects are achieved by the present invention, wherein a valve spring assembly includes a hollow or sleeve-like valve spring plate and a locking element retained by a retainer. The valve spring plate and the retainer form a pre-assembled unit. These components can be installed in a single assembly cycle or together on a valve stem and just as simply removed from it again. It is not necessary to install the valve spring plate first, then to attach the locking element and then to secure these to the valve stem, for example, by a positive locking, connection or a non-positive locking connection. Instead, the valve spring assembly is installed on the valve stem and conducted along it until the locking element makes a locking connection with the valve stem. The valve spring plate is secured to the valve stem and is loaded by a valve spring. The valve spring plate is moved towards the locking element and can be secured by the locking element on the valve stem in the axial direction. In order to disassemble the valve spring assembly or the valve spring plate, the plate can be loaded against the force of the valve spring so that the locking element exits from the sleeve and thereby becomes accessible for the disassembly, for example, with the use of tools, such as a screwdriver.
The retainer may comprise a hinge and/or a spring which can fold over as a function of the load applied to it, so that the locking element can be withdrawn from the valve spring plate. Preferably, at least a portion of the retainer comprises an elastic component, such as a simple and low cost elastic plastic element or rubber element.
The retainer may be a removable component which may be clamped to the valve spring plate or otherwise secured. The retainer can be formed onto the valve spring plate, such as in the form of an elastic sheet metal component. Alternatively, the retainer may be permanently connected to the plate by adhesive, or welding, or the like. The retainer may be a one-piece component or a multi-piece unit. Preferably, it has an inwardly projecting lip clamped in a groove formed in an inner surface of the plate.
Preferably, the valve spring plate has a contact surface which engages the locking element to prevent axial movement of the valve spring plate in one direction. Preferably, the contact area is formed by a shoulder on the plate. The shoulder may be a gradual or abrupt transition.
The valve spring plate may not interact directly with the valve spring, but instead with further components arranged between the valve spring and the valve spring plate. However, the valve spring plate includes a contact area for the valve spring. The contact area is preferably arranged in a rim region of the valve spring plate, or is formed by it, since the valve spring is usually configured as a helical spring through which a valve stem can extend.
Preferably, the valve spring plate includes means for securing the valve spring, so that the valve spring is integrated into the valve spring assembly in such a way that it can be installed together with the valve spring plate and the locking means. Preferably, the plate has a hook-shaped rim which surrounds an opening which receives the valve spring, so that the plate engages and is clamped to an end of the valve spring plate. Alternatively, the spring may be non-removably coupled to the plate, such as by welding, soldering or the like. The spring may also be retained by a simple and cost effective conventional retaining ring, or by retaining disks or snap rings or by corresponding components that preferably interact with an encircling groove in the valve stem.
Preferably, the valve spring assembly includes a valve stem seal which is removably fastened to the valve spring plate so that the valve stem seal can be installed together with the valve spring assembly. Later, it can be separated from the valve spring plate and placed in an operating position.
The valve spring plate includes a recess which releasably receives the valve stem seal. Alternatively, the valve spring plate may have a projection which is releasably received by a recess formed in the valve stem seal. The recess is designed so that the valve stem seal is released when it has reached its operating position on the cylinder head, wherein the valve stem seal is secured on the cylinder head by a clamped connection, by friction locking, or in other ways.
The valve spring plate may be a single individual part and can be combined with the remaining components of the valve spring assembly in a pre-assembly station and then applied together with these other components as an installation unit on a valve stem of an internal combustion engine.
The valve spring assembly may be manually or automatically installed. By combining several components in a valve spring assembly which can be brought to an installation site, the installation process can be accelerated or performed by means of a robot, for example, with a magazine or an automated supply arrangement.